Still to be decided is who joins her in Sochi after two-time defending champ Ashley Wagner finished a distant fourth after a mistake-marred free skate.

Gracie Gold competes during the women's free skate at the U.S. Figure Skating Championships in Boston, Saturday, Jan. 11, 2014.

By not forgetting last year, Gracie Gold did something very memorable in these U.S. Championships.

Gold easily skated off with the women's short program Thursday night with a career-high 72.12 points. Her sensational performance built on strong jumps, improved presentation and a rapport with the audience put her more than five points ahead of 15-year-old Polina Edmunds and nearly seven points ahead of a resurgent Mirai Nagasu.

Athletes to Watch: Sochi 2014

Two-time defending champion Ashley Wagner was fourth.

The top three women will go to the Sochi Olympics. She might settle for Gracie Silver or Gracie Bronze there, but for now, the 18-year-old Gold is on top, erasing bitter memories of her flop in the short program at the 2013 nationals.

Sochi's Winter Olympics Spectacular

"It was one of my best shorts," Gold said. "I feel a little bit different standing here than being in ninth.

"I was able to skate the way I trained. I'm so glad I was able to breathe and bend my knees. I just trusted my training."

She works with renowned coach Frank Carroll, who helped Evan Lysacek win gold at Vancouver.

It worked so well that with a repeat of her superb and victorious free skate from last year, Gold will be a lock for the Olympic team. The long program will be Saturday night following the pairs free skate.

Earlier, hometown favorites Marissa Castelli and Simon Shnapir ignored all the pressure of carrying the hopes of friends and family in the crowd to run away with the pairs short program.

The defending champs staked themselves to a huge lead of 6.63 points.

Gold's triple lutz-triple toe loop combination got her off to a strong start, and the program to "Piano Concerto" kept on building. She earned the highest possible level on all her other elements.

Her performance was no surprise given that Gold is one of the favorites here to claim an Olympic spot. But Edmunds, the 2013 U.S. junior champion, stunned most everyone with her routine as the final skater of the night.

She matched Gold's combination jumps and made her bubbly program look almost easy — as if she knew she belonged in the top echelon.

"It couldn't have been much better," she said. "I shouldn't be surprised. I have all the elements. I just went out and did them."

Wagner didn't test herself the same way, and it cost her. A relatively conservative program also had too many errors, such as a shaky landing on her combination jump, which was only a triple-double. She simply didn't attack the way the top three did.

"I decided to play it safe rather than be sorry," she said. "I could have gone for the triple after the flip, but knew it wouldn't be a good one and it was risky. I decided to just leave it at that."

And that left her fourth, behind Nagasu, who pretty much has struggled ever since finishing fourth in the Vancouver Olympics.

"I feel like I have a full door of opportunity available to me," Nagasu said.

Clearly, so do Castelli and Shnapir.

"We do little exhibitions at our home club, Skating Club of Boston, and those are some of the most nerve-racking performances for us," Shnapir said. "There's almost this feeling of expectation that we have to do well. It's definitely challenging. But as soon as we hit our spot, as soon as we heard our names called, we felt that energy."

Castelli's jaw dropped when their mark of 73.13 points was announced.

"I was in shock at first; I was not expecting that," she said. "I like to try to calculate it in my head. I would have been happy with 66 or 67, so it was just insane."

The crowd was screaming for them from the moment they took the ice to warm up for their performance, the last of the afternoon.

The roars swelled as they skated to "Black Magic Woman" and "Smooth" by Carlos Santana. Their speed on the ice and the height of their jumps were on another level from the rest of the competition, and when Castelli, 23, smoothly landed a big throw triple salchow, Shnapir, 26, might have thought from the reaction that his beloved Bruins had just scored a goal at TD Garden.

"Props to the crowd — that was more than we could have asked for," Shnapir said. "The energy in the house was enormous and it really helped us. It was kind of humbling to know how many people are supporting us and were cheering us on."

The real competition Saturday could be for the United States' second Olympic spot. Felicia Zhang and Nathan Bartholomay lead third-place DeeDee Leng and Timothy LeDuc by 0.1 points.

Caydee Denney and John Coughlin, the 2012 champs, returned after missing last year's nationals as he recovered from hip surgery, and were fourth.